1. Field of the Invention
The present invention relates in general to an air cooling arrangement for a turbocharged internal combustion engine, and particularly, to an arrangement of an intercooler which cools, by using the outside air, the air which is conveyed from a turbocharger to an intake manifold of the engine. More specifically, the present invention is concerned with an arrangement by which the outside air used for cooling the intercooler is reused for cooling particular portions of the intake manifold of the engine for preventing the undesired "vapor lock" and the like.
2. Description of the Prior Art
In order to clarify the task of the present invention, one conventional air cooling arrangement for a turbocharged internal combustion engine will be outlined with reference to FIG. 4 of the accompanying drawings, which is disclosed in Japanese Utility Model First Provisional Publication No. 59-13635.
In the drawing, denoted by numeral 2 is a cylinder head of an internal combustion engine mounted in an engine room of a motor vehicle. A rocker cover 18 is disposed on the cylinder head 2. To one side wall 2b of the cylinder head 2, there is connected an exhaust tube 11 which carries thereon a turbocharger 9, while, to the other side wall 2a of the cylinder head 2, there is mounted an intake manifold 31 which has branch portions curved to extend upward. Denoted by numerals 12 and 13 are fuel injection valves and a fuel conveying tube which are mounted to the intake manifold 31. The turbocharger 9 and the intake manifold 31 are connected through an air-cooled type intercooler 7 which is arranged just above the rocker cover 18. The intercooler 7 is disposed in an air flowing way extending from an air intake bulge 22 formed on an engine room hood of the vehicle, so that the intercooler 7 can be exposed to the outside air (as indicated by the white arrows) which is fed into the way when the vehicle runs.
In operation, compressed and heated air is forced to flow, as indicated by the black arrows, from the turbocharger 9 to the intake manifold 31 through the intercooler 7. In the intercooler 7, heat exchanging is carried out between the heated air from the turbocharger 9 and the outside air from the air intake bulge 22, so that the air practically fed to the engine lowers its temperature. With this, the air charging effeciency of the engine is increased.
However, the above-mentioned conventional air cooling arrangement has the following drawbacks due to its inherency.
First, since the intercooler 7 is located just above the rocker cover 18, the outside air passing through the intercooler 7 is prevented from smoothly flowing toward the intake manifold 31. Thus, cooling for the fuel injection valves 12 and the fuel conveying tube 13 is not effectively achieved, so that the engine tends to undergo the undesired "vapor lock" at idling operation just after high speed cruising of the vehicle and/or at slow movement of the vehicle because of a heavy traffic or the like.
Second, because the intercooler 7 is mounted above the rocker cover 18, the entire height of the engine system is increased thereby narrowing the freedom of design of the vehicle to which the engine system is practically applied. Furthermore, due to the same reason, it is difficult or at least troublesome to change ignition plugs of the engine.